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PubMed1976

Sugar binding to purified fractions from bovine taste buds and epithelial tissue. Relationships to bioactivity.

Binding of various sugars was compared in purified subfractions of taste buds isolated from bovine circumvallate papillae and of non-taste bud-bearing epithelium isolated from tissue surrounding these papillae. Binding of 14C-labeled sugars was greater in purified subfractions obtained from taste bud than from non-taste bud-bearing tissue and was, in general, greater in those taste bud subfractions in which a greater membrane purification was achieved. Binding specificity of the 14C-labeled sugars sucrose, fructose, glucose and of 14C-labeled cyclamate and saccharine was measured by competition of each 14C-labeled sugar or synthetic sweetener with its unlabeled homologous sugar in P4(B) taste bud subfractions; this binding, as shown for sucrose, was reversible and temperature dependent. Essentially no competition of the 14C-lageled sugars sucrose, fructose, glucose or 14C-labeled cyclamate and saccharine by their respective unlabeled homologues occurred in epithelial tissue P4(B) subfractions; this binding was not reversible. Binding specificity was further observed by the competition of 14C-labeled sucrose, fructose and glucose with each unlabeled sugar for binding sites on P4(B) taste bud subfractions; unlabeled sucrose was more effective in competing with each 14C-labeled surgar than was unlabeled fructose or glucose. The relatively non-sweet sugar lactose did not compete with 14C-labeled lactose in P4(B) subfractions from either taste bud or non-taste bud-bearing epithelial tissue. Binding of 14C-labeled sucrose in purified P4(B) bud subfractions was inhibited by increased concentrations of unlabeled sucrose, phospholipase C, neuraminidase, EDTA, NaCl and urea. Dissociation constants for sugar or synthetic sweetener binding were low (approx. 10(-3) M) but in a rank order (sucrose greater than fructose greater than glucose greater than saccharine) consistent with preference and electrophysiological responses in cow. The cow is behaviorally indifferent to saccharine and lactose consistent with the data obtained in the present study.

Animals↗

PubMed1975

Ultrastructure of the taste bud of the human fungiform papilla.

The taste bud of the human fungiform papilla was examined by electron microscopy. Typical type I, type II, and type III cells were found along with contact sites with nerve endings. Vesicles in nerve fibers contacting type I and type II cells suggest that these cells may receive efferent impulses, whereas vesicles and granules in type III cells adjacent to (afferent) nerve fibers support the view that type III cells are sensory receptors. All of these features are virtually indistinguishable from those previously reported in fungiform taste buds of other mammals.

Axons↗

PubMed1979

The occurrence of taste buds in the palate of human adults as evidenced by light microscopy.

There is some uncertainty in the literature as to the existence of taste buds in the palate of the human adult. In those histologic studies in which the ages of the individuals have been reported, taste buds have not been found in the palates of adults, but have been found in fetuses or newborn. However, clinical studies have demonstrated taste perception in the palate of the human adult. Thus, the aim of the present study was to attempt to find taste buds in the human palate in subjects of different ages. In serial sections of selected areas of the palatal mucosa from autopsy material from individuals 0--80 years of age no taste buds could be demonstrated. However, in four of seven subjects aged 25--44 years, one or two taste buds were found in biopsies from areas of the soft palate where taste perception had been demonstrated clinically just prior to excision. Thus the present study indicates that scattered taste buds exist also in the soft palate of human adults.

Adolescent↗

PubMed1976

[Effect of sensory and sympathetic denervation of the frog tongue on the catecholamine containing cells of the taste buds].

The structure of catecholamine-containing dumb-bell shaped cells of the taste buds was studied by luminescent microscopy in the epithelial layer of the frog's tongue (Rana temporaria). On the unilateral section of the lingual nerve, a maintained adrenergic innervation of vessels and of the epithelium was observed, a decreased number of dumb-bell shaped cells in the taste bud, and their significant enlargement, and increased cathecholamine luminescence. With desympathization, no adrenergic nerves were observed on the vessels and the epithelium of the tongue. The size of the taste buds in desympathized cells of the tongue is sharply decreased and their number is increased. There is a tendency to grouping of the dumbbell shaped cells into 3--4 taste buds in one fungiform papillina. The experiments with sensory and sympathetic denervation of the frog tongue distinctly showed the trophic action of sensory and sympathetic nerves on the taste organ of the frog.

Animals↗

PubMed1976

Particular features of the innervation of taste buds of the epiglottis in monkeys.

The work is devoted to the study of the structure of the innervation apparatus of taste buds in the epiglottis of monkeys (Macacus rhesus). The Campos inpregnation method was used. It is established that several afferent myelinated fibers participate in the innervation of each taste bud of the epiglottis. The peculiarity of structure of their preterminal and terminal parts having the appearance of complex windings and spirals is noted. The polyaxonic principle of the innervation of taste buds of the epiglottis in monkeys is considered as a possible mechanism of generalization of the afferent impulses. It is suggested that the innervation apparatus of the taste buds of the epiglottis constitutes part of unique afferent system of this organ, ensuring its defensive function. The incongruity (from the histophysiological standpoint) of the term 'taste bud' in relation to the epiglottis is noted. It is proposed to call these formations special structures of the chemo-receptors.

Animals↗

PubMed1975

Fine structure of taste buds in the rat.

The taste buds of rat circumvallate papillae contain three distinct types of cells. The type I (dark) cell is characterized by the presence of dense round granules, which are precursor to the dense substance of the taste pore. The granules are discharged into the pore by exocytosis. The type II (light) cell is filled with numerous vesicles and smooth-surfaced endoplasmic reticulum. The type III cell contains in its basal cytoplasm characteristic dark-cored vesicles and masses of clear vesicles, and makes synapse-like contacts with nerve fibers. The fine structure of foliate buds corresponds to that of circumvallate papillae, while fungiform buds differ in their apical regions. In the latter the pore is filled with vesicles alone, and the type I cell contains rod-shaped granules of moderate density. When polysaccharides were examined by means of the periodic acid-silver methenamine and the periodic acid-thiocarbohydrazide methods, slightly positive reactions were found on the dense granules of the type I cell and the dense substance in the pore, whereas the membranes of the pore vesicles, apical cytoplasmic processes and cytoplasmic vesicles in type II cells showed intense reactions.

Animals↗

PubMed1978

Taste buds in the vallate papillae of the rat studied with freeze-fracture preparation.

The taste bud of the vallate papillae of the rat has been examined in the electron microscope by using the freeze-fracture technique. Tight junctions as a junctional complex are located at the taste pore, and form a seal between the oral environment and the taste buds. Tight junctions are not only within the taste buds, but also are demonstrated in the granular cell layers of the surrounding lingual epithelium. The present finding suggests that tight junctions of the taste pore link with those of the lingual epithelium. Desmosomes are observed in the buds, but they are smaller in size than in the surrounding lingual epithelium. Besides these junctions, within the buds, gap junctions containing particle-free zones are demonstrated which are called a subcompartment type.

Animals↗

PubMed1976

Fine structure of taste buds in the barbel of the catfish, Ictalurus punctatus.

Taste buds occur in the epithelium of the catfish barbel along its entire length. Two major cell types, light and dark cells, occupy the upper two-thirds of the taste bud. A third cell type, the basal cell, lies on the basal lamina and is essentially separated from the light and dark cells by a plexus of unmyelinated nerve fibers. The dark cells have branching processes, both apically and basally whereas the light cells have a single apical process and many basal processes. The apical processes of dark cells contain secretory granules, while the apical processes of light cells contain an abundant agranular endoplasmic reticulum. Light cell nuclei contain bundles of 10 nm filaments, often arranged in the shape of a cup or ring, but nucleoli are rarely seen. It is suggested that this morphology indicates a low degree of RNA synthesis by light cells. The basal cells contain large numbers of vesicles, about 60 nm in diameter, which are sometimes seen in clumps in relation to an adjacent nerve fiber in a configuration resembling a synapse. Curiously, although basal cells present a large surface to the basal lamina, there are no hemidesmosomes. This suggests that the basal cell does not originate from the epidermis.

Animals↗

PubMed1977

Effect of the length of the distal stump of transected nerve upon the rate of degeneration of taste buds.

The present work was carried out to study the effect of the length of the distal stump of transected nerve upon the rate of degeneration and the time course of disappearance of mammalian taste buds. Twelve adult rabbits were anaesthetized and the glossopharyngeal nerves of both sides were exposed and transected so as to leave a long distal stump on the right and a short one on the left side. The animals were sacrificed at different post-operative periods ranging from 2 to 14 days and the circumvallate and foliate papillae of both sides were examined. The taste buds on the side of the short distal stump always showed a greater decrease in number, size and cell contents than those of the side of the long distal stump. The taste buds on the side of the short distal stump disappeared earlier than those of the side of the long distal stump. Vallate taste buds disappeared earlier than the foliate: possible reasons for this were put forwards. The validity of the neurohumoral theory to the mammalian taste buds was discussed.

Animals↗

PubMed1979

Epithelial differentiation and taste buds in the soft palate of the monkey, Macaca irus.

A combination of light, transmission and scanning electron microscopy was employed to demonstrate the occurrence, arrangement and structure of taste buds in the oral mucosa of the soft palate of monkeys (Macaca irus). Taste buds are found in aggregates confined to 0.15 to 0.3 mm wide, round islands of keratinizing epithelium embedded in the normally non-keratinizing integument. Topography, configuration and structure of these epithelial islands and their taste buds are described, and the question of a developmental and functional interrelationship between epithelial differentiation and properties, and taste bud function is discussed.

Animals↗

PubMedDate not supplied

Catecholamine-containing cells of the taste buds in the tongue of the frog (Rana temporaria).

In a study of the epithelial layer and taste buds of the tongue of the frog using fluorescence, peculiar dumb-bell shaped cells were found in the taste buds of fungiform papillae and these showed a highly-positive reaction to catecholamines. Adrenergic nerve fibres were detected in the vessels of the taste bud and in the epithelium of the tongue. Under conditions of catecholamine deficiency produced by preliminary reserpinization of frogs a decrease in specific fluorescence of the cells and the nerves was observed.

Animals↗

PubMed1979

The distribution of alkaline phosphatase activity in normal and cross-species regenerated rat and mouse taste buds.

Alkaline phosphatase (ALK Pase) activity can be detected histochemically in the taste buds of rats but not mice. Since taste buds develop, regenerate and are maintained under the influence(s) of the sensory nerve it was decided to study cross-species regenerated buds of these two animals to determine whether the nerve also regulated ALK Pase development in taste cells. Grafts of rats sensory ganglion and mouse tongue or mouse ganglion and rat tongue were combined in the anterior chamber of the eyes of immunologically-deficient nude mice and the cross-species buds that developed at 35 days were examined histochemically for ALK Pase. The results revealed that the rat nerve did not cause ALK Pase to appear in any buds found in mouse tongue grafts and that mouse nerve could support buds containing ALK Pase in rat tongue tissue. Because the cross-species regenerated buds were histochemically characteristic of those normally found in rat or mouse tongue, there is no evidence that the foreign nerve altered gene expression for ALK Pase in the target organ, and the action of the nerve on gustatory epithelium appears to be that of activation and maintenance.

Alkaline Phosphatase↗

PubMed1975

On the origin, development and probable functions of taste bud in the lip and bucco-pharyngeal epithelia of an Indian freshwater major carp, Cirrhinus mrigala (Hamilton) in relation to food and feeding habits.

1. Various developmental stages of taste bud have been observed in the fry, fingerling and adult of Cirrhinus mrigala (Hamilton). 2. The fries are zooplankton-feeders (carnivorous) and sight-feeders. Therefore, functional taste buds are absent in the lip and bucco-pharyngeal epithelia. Only formative stages of taste bud are present. Some epithelial cells aggregate together to form this structure which has no function in gustation. Moreover, the fires have low R. L. G. valle (0.71;..1.20) due to the carnivorous diet. 3. In the fingerling, the stages of elongation, differentiation and maturation of taste bund develop from the formative stage present in the fries in order to adjust to changed food and feeding habit. The value of R. L. G; (1.21...3.10) also increases. 4. Fully formed taste buds along with the stage of differentiation are found in the adult stage. The adult fish becomes herbivorous and bottom-feeder. Consequently, the value of R.L.G. 3.11...12) becomes highest in this stage.

Age Factors↗

PubMed1975

Ultrastructural alterations in rabbit taste buds induced by prolonged treatment with cycloheximide.

Prolonged administration of cycloheximide, an inhibitor of ribosomal protein synthesis, induces degeneration of rabbit taste bud cells: the degenerative changes resemble early changes in denervated taste buds. Our observations show that the pattern of degeneration is quite different in the three cell types of the taste buds. The earliest changes in type II and III cells are an increase in cytoplasmic filaments and extreme dilatation of rough endoplasmic cisternae. Profiles of dead type I and II cells vastly increase in number. Type I cells appear less affected by the drug and the only sign of degeneration was an increase in the number of autophagic vacuoles in their cytoplasm. There was no indication that degenerating type I cells undergo transformation to type II or III cells. These findings support our hypothesis that type I, II and III cells represent distinct cell types and do not undergo transformation to other types in the course of their life span.

Animals↗

PubMed1978

Intracellular characteristics and responses of taste bud and lingual cells of the mudpuppy.

Intracellular recordings of membrane potentials of mudpuppy lingual cells were made with micropipette electrodes. Three types of cells were distinguished by their responses to chemical stimulation. Surface epithelial (SE) cells outside of taste buds responded with large membrane potential and resistance changes to a variety of stimuli representing the four taste qualities. Salts and acids evoked particularly large potential changes, and MgCl2, acids, and quinine greatly increased the membrane resistance. One type of taste bud cell (TB-1) was characterized by large depolarizations to K salts, and the other type of taste bud cell (TB-2) characteristically hyperpolarized to MgCl2, acid, and sugar solutions. Membrane resistance changes accompanying TB-1 and TB-2 cell responses were relatively small compared to those of SE cells. Electrotonic coupling was observed between pairs of SE and TB-2 cells but not for pairs of TB-1 cells nor cells of different types. After recording cell responses, dye-marking allowed verification of results in situ and histologically. From the identification of cells in section, it is hypothesized the TB-1 and TB-2 cells correspond to light and dark cells, respectively. Responses of TB-1 cells imply a taste receptive function; wheras TB 2-cell responses suggest secretory, supportive, and (or) receptive functions. Factors affecting cellular characteristics, non-taste bud cell responsiveness, response mechanisms, and function of electrotonic coupling are discussed in relation to taste reception.

Acids↗

PubMed1977

Effect of vincristine on the histological structure of taste buds.

10 adult rabbits were arranged in five batches, 2 animals of nearly the same body weight in each group. 1 animal in each group was injected with vincristine sulfate whereas the other animal was similarly injected with the dissolving medium and used as a control. The animals were sacrificed 2 days after the last injection, and the areas containing the circumvallate and foliate papillae were examined. Injection of vincristine was followed by a decrease in number and in cell contents of vallate and foliate taste buds. Most of the taste buds which persisted after vincristine injection were full of necrotic debris which represented the remnants of degenerated cells. Possible reasons for degeneration of taste buds after vincristine injections were put forewards.

Animals↗

PubMed1978

[Modulating effect of the salivary glands upon differentiation and maturation of taste bud cells in the rat (author's transl)].

It is currently considered that the sensitive nerves of the papillary plexus are solely responsible for the normal differentiation of taste bud cells in the circumvallate papillae of the rat. The effect of syallectomy on taste bud cells was studied. Evaluation of results was performed through cell counts. The results demonstrate that the major salivary glands are quite important in both differentiation and maturation of taste bud cells.

Cell Count↗

PubMed1976

An ultrastructural study on the development of vallate taste buds of the golden Syrian hamster.

An ultrastructural developmental study of hamster vallate taste buds was undertaken to demonstrate the sequential morphodifferentiation of their various cellular components. Under the neurogenic influence of the glossopharyngeal nerve, the undifferentiated epithelial cells of the vallate papilla first acquired fine structure features similar to those seen in the perigemmal adult peripheral cells and the gemmal basal cells. As the development progressed, the relatively undifferentiated basal cells appeared to differentiate into dark and light cell precursors. Mature light cells were frequently noted chronologically before any fully mature dark cells were observed. Transition from light to dark cells, or vice versa, was not noted at any time throughout the investigation, suggesting that light and dark cells originate as separate cell lines from the basal cells of the taste bud proper.

Age Factors↗